Process for heating horizontal coke oven batteries



United States Patent 3,175,959 PROCESS FOR HEATING HORIZONTAL COKE OVEN BATTERIES Kaspar Heinrich Osthaus, Fritz Rose, Adolf Linke, and Hans Wagner, all of Essen, Germany, assignors, by mesne assignments, to Koppers (Iompany, Inc Pitts= burgh, Pa., a corporation of Delaware N0 Drawing. Filed Nov. 13, 1961, Ser. No. 152,066 1 Claim. (Cl. 20212) The present invention relates to a process for heating horizontal coke oven batteries by means of a combustible gas containing gasoline (benzine or similar low-boiling hydrocarbon fractions).

Horizontal coke ovens for the production of gas and coke are normally heated with a portion of the produced coke oven gas itself or also with blast furnace gas or producer gas. In order to release more coke oven gas, in more recent times the heating of coke ovens has also been effected with other heating gases, particularly with such gases which contain considerable amounts of liquefied gas or gasoline vapors. A 100% replacement of coke oven gas has been achieved by preparing a mixture of gasoline vapors, flue gas and air, the heating value of which corresponds to about that of the normal coke oven gas; in this case, the addition of air amounts to between 10 and 20%, calculated on the total mixture.

It has now been found that the operation of underfiring with heating gases containing gasoline may be essentially simplified when certain conditions are simultaneously maintained. Accordingly, the present invention consists in heating horizontal coke ovens by means of a mixture of gases which consists exclusively of gasoline vapor and flue gas, in which case the oxygen content of the gaseous mixture is maintained under about 5% and the heating value of the mixture is maintained constantly within a range of 3600-3900 kilogram calories per normal cubic meter. According to the invention, the reversal times of the heating are simultaneously reduced, preferably to 812 minutes, in comparison with a heating with coke oven gas or with lean gas. Furthermore, the heating gas nozzles of the heating lines, which are farthest removed from the inlets of the mixture of heating gas to the distributing duct of the coke oven, are designed so as to have up to a 40% greater area for flow of heating gas, in comparison to operation with coke oven gas.

The apparatus for preparation of the mixture of heating gas can be simplified by the present invention. The mixing device has to mix only two components, namely gasoline vapor and flue gas, and a blower for the air to be admixed in accordance with the other suggestions is omitted. Furthermore, by the limitation of the heating value within the given limits, the formation of soot in the distributing duct for the mixture of heating gas is suppressed; this is also conducive to a shortening of the reversal times. By the improvements conforming to the invention, it is possible to maintain a uniform heating of the heating walls, while raising the temperature in the end heating flues, in the case of an underfiring requirement which is only about 5-10% above the value which is needed for normal rich-gas operation.

It has been shown that the heating value of the mixture of gasoline vapor and flue gas is advantageously maintained constant in a narrow range as previously cited, preferably in a range between 3650-3850 kilogram calories per normal cubic meter.

A mixture of petroleum hydrocarbons having a boiling range of 40-150" 0, preferably a boiling range of 30- 100 C., is advantageously used as gasoline (benzine or similar low-boiling hydrocarbon fractions).

The flue gas which is used for regulation of the heating value of the mixture of heating gas should advantageously 3,175,959 Patented Mar. 30, 1965 contain very little sulfur oxide. The use of flue gas which is formed by combustion of the mixture of gasoline vapor and flue gas is particularly favorable.

The invention is further illustrated by the following example. A coke oven in which the end flues are heated to a higher temperature and the heating walls of which consist of 28 heating flues that are connected in pairs in accordance with the recirculation principle (automatic admixing of flue gas) was underfired in accordance with the present invention.

The weight of a charge of an oven chamber amounted to 19.8 tons of coking coal with a moisture content of about 9%. The operating time, i.e., the period of time between charging the chamber and pushing of the completely coked coke, amounted to 21 hours. The average temperature of the heating wall was about 1300" and the average temperature of the waste gas was about 323 C. The waste gas Withdrawn from the battery had a carbon dioxide content of 10.6% and an oxygen content of 3.5%. However, it should be understood that an oxygen-rich line gas containing, for example, 5% oxygen can also be used for preparation of the mixture of heating gas. However, the oxygen content of the flue gas should not amount to more than about 6 7%, namely the oxygen content of the mixture of heating gas should not amount to more than about 56%.

Calculated on the heating of a single coke oven wall, the proportion of flue gas in the mixture of heating gas mounted to cubic meters (under standard conditions) per hour and the proportion of gasoline vapor amounted to about 13.8 cubic meters (under standard conditions) per hour. The mixed gas had a net calorific value of 3750 kilogram calories per normal cubic meter. The density of the mixed gas amounted to 1.15. The mixed gas was introduced into the rich-gas distributing duct at a temperature of about 53. The pressure of the mixed gas in the distributing duct amounts to +6 mm. water column.

Since the mixed gas entered the distributing duct from both sides, the nozzle located in the center was widened from 31 mm. diameter to 34 mm. and the two nozzles adjacent to the middle nozzle were widened from 31 mm. to 33 mm. diameter. The reversal time amounted to 10 minutes. The gasoline used had a gross calorific value of 11,560 kilogram calories per kilogram. The underfiring requirement, i.e., the expenditure of heat per kilogram of charged coal (calculated on a moisture of 8% was practically the same as that of rich-gas heating, when the fact is considered that, because of the greater amount of flue gas which is formed upon heating with the mixed gas, somewhat greater losses of waste gas occur; moreover, an increase of the temperature in the end heating flues results from heating with the mixed gas. All things considered, the underfiring requirement upon heating with mixed gas in the manner conforming to the invention is about 5-10% higher than in the case of heating with rich gas, and is dependent on the coking time.

The present invention is explained in the example for coke ovens in which the end flues of the heating walls are heated to a higher temperature. Investigations have proven that even coke ovens in which the end flues of the heating walls are heated to a higher temperature, in which a substantial formation of soot by cracking of the gasoline in the distributing duct of the heating gas (horizontal duct) must be expected in accordance with previous experience, may be underfired completely free from difficulty with a mixture of heating gas consisting only of gasoline vapor and flue gas under the conditions conforming to the invention.

The process conforming to the invention may also be used in coke ovens designed for underfiring heating with the advantages prevailing in more simple apparatus.

It is claimed:

A process for heating the walls of a horizontal coke oven battery which comprises: mixing a minor quantity of gasoline vapor With a major quantity of flue gas that has been formed by the prior burning of gasoline vapors in the coke oven walls to form a mixture having an oxygen content of less than 6% and a heating value of 3600 to 3900 kilogram calories per normal cubic meter, said gasoline having a boiling range of from 30-150 C. and burning said mixture in the walls of said coke oven to provide heat therefor and to provide additional flue gas for further mixing with gasoline vapor and subsequent heating of said coke oven.

References Cited by the Examiner UNITED STATES PATENTS 1/49 Keeling 202-12 MORRIS O. WOLK, Primary Examiner.

10 ALPHONSO D. SULLIVAN, JAMES H. TAYMAN, JR.,

Examiners. 

